The present invention relates to an attachment structure of a key top used in a small-sized electronic equipment such as an inter-call receiver, or the like, and particularly relates to a key top attachment structure in which the structure of the key top is simple and the key top can be easily attached to a casing and held stably.
One or more switches are provided in a small-sized electronic equipment such as an inter-call receiver, or the like. A key top which is good and stable in manipulability of the switches and which is low in manufacturing cost has been desired.
Examples of conventional key tops include: a key top which has a stopper and which is pressed into a casing having a lock portion in which the stopper of the key top is locked; and another key top which has an elastic stopper and which is inserted into a casing while the stopper is being bent. A further key top is disclosed in JP-U-6-79042, which is provided with an arm having spring property for suppressing looseness and clattering between the key top and a casing.
Of the conventional key tops, the key top having a stopper pressed into a casing needs high-precision parts in order that the key top can be assembled while it is difficult to be taken off. If there are large variation in dimension of the parts, there is a problem that the key top or the casing is damaged or deformed at the time of assembling, or the key top is detached from the casing in use.
On the other hand, as for the key top which has an elastic stopper and which is inserted into the casing while the stopper is being bent, the key top is inevitably increased in size so as to obtain proper bending property of the stopper. Thus, there is a problem that a large space is required for installation of the key top.
On the other hand, the operation of the key top becomes heavier if there is provided a spring for eliminating looseness between the key top and the casing in order to prevent abnormal sound from being generated by vibrations caused by a calling vibrator or speaker singing in an intercall receiver. If a spring with a light load is used to make the key top operation lighter, a larger space is required. If such a spring is provided, the spring cannot be formed through resin molding integrally with the casing, and the spring has to be manufactured as a separate part. Accordingly, the number of parts increases, and the structure becomes complicated.